RomRaider

Hi everyone, I'm new to the forum and I've done a lot of reading regarding MS41 ECUs, RomRaider, and tuning. I'm hoping someone knowlegable will be able to help me (No I'm not asking for someone to tune the car for me like most people do here).

I'm running an M50B25TU engine with M5430 intake cam and M52B28 exhaust cam in my E36, I did a full conversion to Siemens OBD2 Electronics (all sensors swaped, complete engine harness, followed by an MS41.0 ECU, yes it has an Index"xx" so I know it's tunable) so it's basically like an M52B25 with M50 intake, cams, exhaust manifold followed by fully done exhaust system.

My question is, from which engines partial file would be my ideal starter? I looked up the VIN number from ECUs sticker and it shows that the ECU is from 323i, the guy I got it from says that something has been done to the ECU but he has no idea what....

I ordered the cables that I need for the job, they should arrive in a few days, and I also bought MS41 Quickflash program.

I hope someone will have some kind of advice for this setup since I haven't seen many people do this to an M50 engine.

Thank you everyone in advance!

Probably best off to start with a clean BIN. M50 b25 is an iron 2.5L block right? So you can start with just about any iron block BIN and tune from there. I would probably start by disabling any identified DTCs for deleted components. Then work on smoothing idle out, and tune fuel then timing from there.

Exactly busterhax, it's iron block, all the emissions stuff is deleted, I'll try to start the car tomorrow, and I will post the result here, and once the cables arrive and I manage to read what's on the ECU currently, I will post it here as well. And I don't think I can find an M50B25 bin here since that is BoschMotronic, if I'm wrong and there is a file or something similar, please do provide the link.

Theres a large thread of stock BINs.

UPDATE:

I connected everything, fuel pump primes, car cranks but it won't start, the engine harness that I installed is from an automatic, my guess is that since I don't have an Automatic Transmission ECU pluged in that something is stopping the car from starting. Once I manage to get everything working I will post a detailed step by step what did I have to do in order to get everything to work.

Definitely dont need the auto ecu connected, but you may need to bridge the wires for the Park/Neutral switch - Pin 2 (brown/violet) and 52 (violet) on EGS ecu connector.
Have you done the basics, like confirming that EWS is disabled?

I also ran an m50b25tu on siemens ms41.2.

I have no idea if the EWS is disabled, my OBD2 cable is supposed to arrive today, and I'm waiting for BMWs x20 connector to OBD2 adapter cable, that is supposed to arrive this week, I might have found the no start problem, the car has spark and has fuel and kinda "pops" while cranking, kinda like it wants to start but just can't get it together, I checked the resistance in the crank sensor and it's dead, so until I recieve my cables for reading and flashing the ECU and the new crank sensor, I'm kinda stumped and have to sit and wait...

Do you mind sharing some info about what you did to the ECU, what base map did you use and stuff like that to get the car runing so that it is drivable every day ?

A simple search for my project thread here should answer your questions....

Try get the car running on starter fluid. When i had a malfunctioning crank sensor, it wouldnt start unless i used starter fluid to get it going. After than it would continue to run.

Well here I am after some time, all my equipment arrived, sadly couldn't get my Quickflash program activated so I used good ole chipster, INPA shows only Lamba 1 code, and tank ventilation (EVAP is deleted so it's understandable) here is the full read and partial read of the ECU that is on the car, the car still doesn't start so I hope someone will be able to help me to continue to troubleshoot, the car has spark, has fuel, gets air, kinda pops a bit on the exhaust when I crank it but still doesn't start. I changed the crank sensor with a new VDO one and I managed to get my hands on an OEM cam position sensor.

as far as i remember trigger wheel on crankshaft is different in bosch and siemens applications
check it

True, that is why the crank pulley has also been changed to the one from an M52 engine, I'm currently taking a quick break from working on the car since I'm re-timing the engine, didn't look like it was timed properly by the previous guy.... Will post results as soon as I make some kind of progress.

Not entirely. M50B25tu (bosch) has the same crank trigger wheel as the M52.

Confirming this, I just put them side by side, they are same, as for my no start problem goes, the cam sensor was indeed the problem, it didn't pop out as code on INPA but when cranked while logging the parameters were jumping around like crazy, so I ordered the new cam sensor that will arrive in 3-4 days so when I have an update I will post, also want to thank ba114, some of your older posts and advices really helped me realise and re-check some things on my car, cheers to you for sharing your knowledge man!

Well after a lot of trial and error finally managed to start the car..... the problem was that someone at some point of this engines life changed the crank to an M50 non-vanos one, so no matter how many times I retimed the engine while the crank pulley was installed the way it was ment to, the first tooth of the pulley that the engine reads was always wrong, rotated the crank pulley and voila, the car finally started, now my new problem is that as soon as it starts without touching anything the car instantly goes to the limiter... sooo any ideas guys ?

Finally.... everything is finished, the high idle was just a stuck throttle cable *facepalm*
So for people who come across my post loking for a solution on how to convert their M50B25TU to MS41 here is how I did it.

Things you will need:
-OBD2 Engine wiring harness
-IAT Sensor (OEM BMW Part number 13621739510, but I went to the local auto store and got the first thing they had in stock and works fine so no need to spend big bucks, asked for an M52B28 E36, make sure it has a round 4 pin connector, it won't fit the stock M50B25 manifold, you have to grind it down and thread it to m12x1.5 or just grind it down until it fits the hole and make sure to seal it with silicone, I used the Victor Reinz gasket silicone)
-Coolant temp sensor (OEM BMW Part number 13621703993, same thing as above, no need to bang out big bucks on an OEM one, the replacement one works fine too)
-2x O2 Sensor (NGK/NTK ones work amazing, part number 11781437943)
-Crank sensor (OEM BMW Part number 11781437943, get VDO-Siemens or an OEM one only)
-Cam sensor (OEM BMW Part number 12141703221, same sa crank sensor VDO-Siemens or OEM one)
-MAF can stay Bosch
-TPS can stay Bosch

How to put it all together:

Firstly take of the intake manifold so it would be much easier to unplug all the sensors and remove the harness, make sure you undo everything and don't be dumb like me and forget the two little connectors on the starter....
After you removed the harness, you can easily start removing the sensors and instaling the new ones, put the new harness in and plug everything back together, it's pretty straightforward, not very complicated, after that reflash your ECU because it probably has EWS enabled (there are treads on here and youtube videos that will show you how to disable it).
After you have done everything that should be it.

I know there are many posts about OBD1 to OBD2 conversion and that it's very simple, but I tought I would share the info that I learned and gathered from multiple sources to maybe help someone out in the future.

Good luck to everyone who reads this, and a huge thank you to the people of this forum that share their knowledge with everyone!